Use of a cable network to broadcast programming content, e.g., TV programs, is well known. However, it has been proposed in the cable industry to record in-progress TV broadcast programs at a headend of the cable network, thereby enabling a user to manipulate the recorded programming content to perform such network personal video recorder (NPVR) functions as “pausing,” “rewinding” and “fast-forwarding” on the programming content while it is being broadcast. The network architecture and functionalities required to effect these NPVR functions are described, e.g., in copending, commonly assigned application Ser. No. 10/263,015 filed on Oct. 2, 2002, hereby incorporated by reference.
Although providing users with NPVR functions enhances users' program viewing experience, the requisite network processing, e.g., recording programming content and accessing the recorded programming content in the headend, to effect such functions causes the recorded program stream to lag behind the broadcast program stream. That is, the recorded program stream received by a first user afforded the NPVR functions is a delayed version of the broadcast program stream received by a second, non-NPVR user. The unsynchronization of the two streams may be so significant that when the first and second users are communicating with each other (e.g., on the phone) on what they are viewing on TV, the first user is able to notice a delay in receiving the same information which the second user already received. As a result, the first user may feel “behind” the second user in receiving such real-time information as instant sports game scores and breaking news, which unsynchronization may be undesirable.
In another NPVR implementation, an NPVR user may experience the undesirable unsynchronization effect firsthand when the user receiving a recorded program stream is switched to receiving the corresponding broadcast program stream, and vice versa. In that implementation, an NPVR user is initially afforded a broadcast program stream until the user performs one of the NPVR functions, say, rewinding the programming content being broadcast. At such time, the user is switched from receiving the broadcast program stream to receiving the corresponding recorded program stream to perform the rewinding function. However, such stream switching may result in viewing repetitive programming content for the duration of the lag of the recorded program stream behind the broadcast program stream. Conversely, when the NPVR user, after performing the rewinding function, fast-forwards the programming content in the recorded program stream and catches up with the programming content being broadcast, the NPVR user may be switched back to receiving the broadcast program stream. However, such stream switching may result in skipping ahead the programming content being viewed, thereby undesirably creating an information gap which corresponds to the time lag of the recorded program stream behind the broadcast program stream.